CHRONIC SINUSITIS 77 polypi intranasal ethmoidectomy is rarely performed because access is limited and adequate drainage of the labyrinth of cells is not easily achieved. External ethmoidectomy is recommended for chronic infection of the ethmoidal sinuses with evidence of complications, usually an extension into the orbit. It is also performed for frequent recurrences of nasal polypi which are not controlled by simple removals and when a more radical cure is desirable. The standard operation is through an incision around the inner Fig. 35. Radical frontal operation. A, Incision. B, Opening of frontal sinus. C, Ethmoidal cells opened and drainage into nose created. canthus through which the ethmoidal labyrinth is reached and the cells exenterated ensuring a wide drainage into the nasal cavity. The incision is closed and the stitches removed in a week. The after-treatment is that of external frontal sinus operation. The Patterson operation is an external ethmoidectomy in which the incision starts near the inner canthus and extends downwards and laterally in the natural fold between the lower eyelid and the cheek, thus achieving an almost invisible scar. The exposure of the ethmoidal cells is claimed to be much wider than in the standard approach.